Concrete is the result from mixing hydraulic-activated binding materials, such as cement, with inert solid granular materials with suitable particle size and water. Said mixture consists of moldable slurry with adhesive properties that after setting becomes a stony consistency material.
One of the main features of concrete is its resistance against compression forces; however, its behavior before other forces such as traction, flexion, abrasion, etc. is not the best. In order to modify the concrete's characteristics and behavior, a common practice is to add additives.
Currently, in cement, concrete, and construction industry, in general, environmental awareness has been encouraged, intensifying awareness and actions towards these matters. Environment is a fundamental part of sustainable development to absorb effects of human activity, proposing science and technology improvements.
One of the environmental aspects to be considered is water: groundwater recharge and pollutant elimination. A method used and improved in the last decade for correcting the above mentioned aspects is the use of permeable concretes in roadway. This action allows groundwater recharge, filtration of pollutants towards groundwater, and reducing infectious focus by decreasing ponding.
Previous concrete is a well-known ecological and environmentally friendly material; however, it shows deficiencies in resistance, durability, degradability, etc.
Additives for manufacturing pervious concrete and methods for manufacturing them have taken many forms. For example, in the prior art, Mexican Patent No. 270,135 (Jaime Grau G., et. al.) describes an additive for manufacturing permeable ecological concretes with high-resistance for compression, flexion, and abrasion that allows water filtration to subsoil. Said additive, by being mixed with cement, water and any hard aggregate results in a high-resistance and long-durability concrete. The additive is prepared based on dispersants, binders, moisturizer agents, hydroxypropylethyl cellulose or hydroxypropylmethyl cellulose, and silica aluminates, water, surfactants, bactericides, and defoaming agents.
In addition, in Mexico there is a protection of Patent No. 236,456 from Halliburton Energy Services, Inc. for an improved permeable cement composition including an effective amount of a surfactant. By adding surfactant to permeable cement composition provides at least a pumpable grout with a minimum amount of water or brine.
Document US 2009/0197991 A1 (Construction Research & Technology GmbH) discloses a cement-water composition, and a rheology modifying additive (RMA). By including RMA, the cement composition is improved. The protected composition may include other additives already known in the state of the art.
It is a common practice in the state of art to find patents related to additives for concrete and/or cement compositions, as is the case of U.S. Pat. No. 3,948,672 to Texaco, which grants protection to a permeable cement composition for treating and fixing a permeable concrete film of the barrier between the formation and the well.
U.S. Pat. No. 6,875,265 B1 (Sung Soon Kang), grants protection to an improved high-performance cement including the established amounts of aggregates, cement, water, dyes, charcoal powder, etc. that results in a product with a 120-300 kgf/cm2 compression force and 2×10−2 cm/sec permeability coefficient.
It is important to mention that despite the existence of various additive mixtures for manufacturing permeable concretes and/or permeable compositions in the state of the art, several deficiencies exist. There is a need for new additives and/or cement compositions that efficiently solve the following problems:
Additives of the state of the art must be manually added in situ, rather than automatically at the concrete production plants causing that an automatic dosing can not be made and to have in dosage errors due to the manual dosage.
Setting times are short leading to add water continuously and consequently getting out of technical specifications needed for the proper and/or efficient performance of concrete.
Working and/or placing concretes of the prior art in warm weather are complicated at daytime because hot weather substantially affects the admixture, shorting even more setting times and the concrete placement at overnight increases the application costs.
Cement placement requires constantly wetting the base before placing concrete to avoid water absorption, which causes low humidity and consequently cracks on the surface.
For the curing process, once the cement of the prior art is placed, it is required to place polyethylene sheets on the surface. This is a problem because the wind lifts the polyethylene sheets, resulting in bad setting, cracks and decay on concrete surface.
Pervious concrete has poor plasticity and/or handling.
One of the main deficiencies is the use of high percentage of additive with relation to the amount of cement.
Cement of the state of the art is expensive because very high thickness must be used to reach the intended high resistance. Therefore, this cement is only used in low traffic sites like pathways, sidewalks, bicycle paths, parking lots, etc., where high resistance is not critical.
Thus, the above mentioned documents of the state of the art neither disclose nor suggest the composition and/or additive within the scope of the composition discloses in this application, that is an additive for permeable concretes with improved properties, which can be added to any type of stony aggregate and/or cement, improving mechanical properties required for the product on each step before, during, and after of the setting.